We just aren't really taught to visualize our weights and measures, it's why newscasters keep saying shit like "8 Olympic swimming pools!" Or "the size of three football fields"
This really isn't an American thing - it's just human, we can't really visualize dimensions accurately unless we have a good reference. Some may measure the Olympic swimming pool in feet others in meters, but the effect is the same.
Really? ... Am I super weird then? Because I can visualize volume and distance really well. I just assumed that was being, like, literate in both systems of measure.
Everyone can visualize volume and distance really well in their own head. Doesn't mean they're right. Try it for yourself, maybe you're gifted?